In order to achieve ultra-high-speed wireless transmission, the RIS assisted ultra-wideband wireless communication will be an important trend. However, the beam squint effect caused by the ultra-wideband communication brings a serious challenge for the channel estimation, since the single physical angle will be transformed to multiple spatial angles. [1]} proposed a beam squint pattern matching based wideband channel estimation in the conventional wireless communication system. The similar idea may be applied in the wideband channel estimation for the RIS assisted wireless communication system.
